The present invention relates to agricultural machines and more particularly to harvesting machines which, as part of the harvesting process, cut the crop or the plants on which the crop was grown. The invention provides an automatic steering control capable of locating the crop line between cut and uncut crop, steering the harvesting machine along the crop line as it traverses a field, sensing the end of a crop row and, upon reaching the end of the crop row, controlling the turning of the harvester to begin a new traverse of the field.
In recent years many of the functions of harvesting machines normally controlled manually by an operator have been automated. Audible and visual sensing by the operator have been replaced with optical, sonic, magnetic, radio frequency and other types of sensors. Microprocessors operating in response to conditions sensed by the sensors have replaced manual operator control of the mechanical functions. However, it is still necessary to have an operator for steering the harvester to (1) move along a crop line, (2) turn the harvester when the end of a crop row has been reached, and (3) avoid obstacles which may be present in the field.
If the need for an operator can be eliminated, it would not be necessary to provide a cab for the harvester or the many operator comfort features such as air conditioning, stereo, etc. now provided on many harvesters.
Even if the need for an operator is not completely eliminated, it is still desirable to provide some form of automated steering or xe2x80x9ccruise controlxe2x80x9d to lessen the burden on the operator and increase the efficiency of utilization of the harvester. While an operator may easily steer a harvester along a crop line at speeds of about 4 to 5 miles an hour, the constant attention required to accomplish this is extremely tiring and an operator can not maintain this speed for long periods of time. The efficiency of utilization of the harvester could be increased by providing a form of cruise control which steers the harvester along a crop line at the maximum harvester speed and either stops the harvester or signals the operator to take over manual control of the steering as the harvester approaches the end of a crop field.
The invention provides a robotic control system for an agricultural harvester, the robotic control system comprising an execution monitor module which is sequenced through a plurality of finite states by trigger messages from a field coverage planner module, a global trajectory tracker module, a controller module, an end of row detector module and a field coverage monitor module, the execution monitor module activating at least one of the field coverage planner module, the global trajectory tracker module, the end of row detector module, a crop line tracker module or a local trajectory tracker module in each finite state so as to generate steering signals for steering the harvester along a path specified by a field coverage plan to cut all crop in a field.
The global trajectory tracker module generates votes indicating the preferred direction the harvester should be steered so as to follow the path and the crop line tracker module generates steering votes on the direction the harvester should be steered to follow a crop line between cut and uncut crop, the system further comprising a continuously running steering arbiter module for developing steering commands from all the steering votes, and a continuously running controller responsive to the steering commands for developing signals to differentially drive front wheels of the harvester to steer it.
According to one aspect of the invention, the robotic control system includes at least one and preferably two alternately active video cameras mounted on the harvester for viewing the changing scene in front of the harvester and producing images thereof as the harvester moves along the planned path, a frame grabber for grabbing one image at a time from the active camera, and a video processing computer for analyzing each image pixel by pixel according to a color discriminant function to locate a crop line between cut and uncut crop, the color discriminant function being adaptively updated by computing, as the discriminant used in analyzing one image, the Fisher linear discriminant in RGB space between the cut and uncut pixel classes for the preceding image. Prior to analyzing each image to locate the crop line, the image may be compensated for shadows.
According to another aspect of the invention, the robotic control system includes at least one and. preferably two alternately active video cameras mounted on a harvester for viewing the changing scene in front of the harvester and producing images thereof as the harvester moves along the planned path, a frame grabber for grabbing one image at a time from the active camera, and a video processing computer for analyzing each image pixel by pixel and scan line by scan line to locate, for each scan line, a crop line point between cut and uncut crop if there is a crop line imaged in the scan line, and determining which scan line is most likely imaging the end of a crop row.
According to a further aspect of the invention, the robotic control system includes at least one and preferably two alternately active video cameras mounted on a harvester for viewing the changing scene in front of the harvester and producing images thereof as the harvester moves along the planned path, a frame grabber for grabbing one image at a time from the active camera, and a video processing computer for analyzing each image pixel by pixel to determine the probability that a region of the image surrounding each pixel is imaging an obstacle in the path of the harvester.